This invention is directed to a process for preventing an extensible web from elongating excessively during handling or converting.
Extensible materials are commonly used in the manufacture of personal care absorbent articles. Converting elastic and extensible materials, namely unwinding the material from a roll or a spool and then performing some operation on it, can be difficult, since some finite tension is required on the web as the web travels through the converting process. Examples of common converting processes include rewinding, spooling, slitting, laminating, or incorporating a web into a complex product such as a diaper.
Converting processes impart tensile forces on a web causing the web to elongate, either permanently or temporarily, thus causing the web""s elongational state to change during the process. The effects of the tensile forces can range from minor to extreme. For example, if the material is simply being rewound, then the material""s elongational state may be different on the receiving roll versus the feed roll. However, if the material is being converted into a diaper, the elongational state during the process may be so significantly altered as to cause improper placement of diaper components.
There is a need or desire for a way to stabilize an extensible material during handling or converting without eliminating the extensibility of the material.
This invention is directed to a process for preventing an extensible web from elongating excessively during handling or converting. The process of the invention temporarily stabilizes the extensible web and, once the converting is done, returns full extensibility to the material.
The extensible web used in this invention may be a fibrous material such as, for example, a spunbond web, a meltblown web, a bonded carded web, or a combination thereof. The material may be made of an elastomeric fiber forming polymer.
In carrying out the process of the invention, the web is bonded in specific areas to render the web rigid. The bonding may be, but is not limited to, thermal, ultrasonic, or adhesive bonding, and may stabilize the material against stretching in one direction or in multiple directions. The bonding is suitably oriented in a direction of extensibility of the extensible material, and may also be oriented in other directions non-parallel to the direction of extensibility of the extensible web. Furthermore, the bonding may be either continuous or segmented, and the segmented bond lines may cover varying percentages of the extensible material in the direction of extensibility. The areas that are bonded are suitably areas of the web that will be trimmed or cut away during the converting process.
The converting process may include, but is not limited to, winding the bonded material onto a roll, spooling the bonded material, slitting the bonded material, laminating the bonded material, or incorporating the bonded material into a garment. The extensible material can be incorporated into any suitable personal care garment, such as a diaper, a training pant, a feminine hygiene product, an incontinence product, or a medical garment.
In one embodiment of the invention, the bonded regions may be along the edge regions of the material. By bonding along the edge regions, the bonded regions can easily be removed when stabilization is no longer necessary without disrupting a central region of the material. In this embodiment, the removal of the bonded regions may not require an additional manufacturing step if the bonded regions are located in portions of the material predestined for removal, for example for sizing and/or shaping of a garment made from the extensible material.
In another embodiment of the invention, the bonded regions may be in a central region of the material. The bonded region is then slit to create two pieces of material, each stabilized along one edge. Consequently, the bonded edge regions can easily be removed when stabilization is no longer necessary without disrupting a central region of either of the two pieces of material.
With the foregoing in mind, particular embodiments of the invention provide a process for stabilizing an extensible material during handling or converting without eliminating the extensibility of the material.
The foregoing and other features and advantages of this invention will become further apparent from the following detailed description of the preferred embodiments, read in conjunction with the drawings.